Hormones

• A hormone is a chemical messenger that is produced by a gland and travels in the blood to a target organ.
• Thyroid Gland

  • Produces the hormone thyroxine
  • Regulates the base of metabolism
  • Excess causes hyperactivity
  • Deficiency causes overweight and sluggishness
  • Levels of thyroxine are controlled by thyroid simulating hormone (TSH) - which is secreted by the pituitary
  • TSH is released when body temperature falls
• Adrenal Glands

  • Produces a hormone called adrenaline, which causes a 'fight or flight' response
  • Increases heart and breathing rate
  • Blood is diverted to the muscles
  • Increases respiration and blood glucose levels
• Pancreas

  • Produces insulin
  • Acts to decrease blood glucose
• Glucagon

  • Acts to increase blood glucose
• Ovaries

  • Produces oestrogen
  • Controls the development of female sexual characteristics
  • Regulates the menstrual cycle
• Progesterone

  • Maintains the uterus lining
• Testes

  • Produce testosterone
  • Promotes the development of male sexual characteristics
• • Usually the body reacts slowly to hormones as they coordinate long term body changes
  • However, adrenaline acts quickly
• • Negative feedback is a control system in which any change away from the optimum level is reversed
  • Negative feedback prevents a system from becoming overactive
  • The system is inhibited by its own products
• Adrenaline effects on the body - heart rate (heart)

  • More blood carrying glucose and oxygen
  • Heart rate increases
• Adrenaline effects on the body - breathing rate (lungs)

  • Provides more oxygen in the blood
  • Removes CO2
  • Breathing rate increases
• Adrenaline effects on body - glucagon converted glucose(liver)

  • More glycogen is converted into glucose
• Adrenaline effects on body - Blood flow(muscles)

  • Increases blood flow
  • Supplies more glucose and oxygen
  • Muscle cells respire quicker in response to fight or flight.
• Adrenaline effects on body - glucagon released (pancreas)

  • More glucagon is released
  • Insulin production is reduced
• Adrenaline effects on the body - blood supply (brain)

  • Increased blood supply
  • Increases glucose and oxygen supply to the brain